Switching circuit



March 1959 R. E. LOUDON ETAL 2,877,387

SWITCHING CIRCUIT Filed Sept. 3, 1957 United States Patent Ofitice 2,877,387 Patented Mar. 10, 1959 SWITCHING CIRCUIT Robert E. London, Los Angeles, and Vernon G. Skare, La Mirada, 'Calif., assignors to Clary Corporation, a corporation of California Application September 3, 1957, Serial No. 681,492

8 Claims. (Cl. 315-240) This invention relates to bi-stable switching circuits and has particular reference to a trigger type switching or flip-flop circuit which embodies a single input circuit and has two settable states or conditions, in which the circuit assumes one state upon reception of a first signal from the input circuit and assumes a second state upon reception of a second signal from the input circuit.

A principal object of the present invention is to provide a trigger type bi-stable switching circuit which is simple in construction and economical to manufacture.

Another object is to provide a simple trigger type bistable switching circuit capable of handling relatively heavy electrical currents.

Another object is to provide a trigger type bi-stable switching circuit which does not require expensive high quality components and which will yet operate under a wide range of control voltages.

A further object is to provide a trigger type bi-stable switching circuit embodying a relay which is effective when in energized condition to assume one state and when in a deenergized condition to assume a second state.

The manner in which the above and other objects of the invention are accomplished will be readily understood on reference to the following specification when read in conjunction with the .accompanying drawing, wherein the figure comprises a schematic view of a preferred form of the present invention.

Referring to the drawing, the circuit comprises a relay 11 whose coil is connected at its lower end to a source 12 of B plus supply and whose upper end is connected to the anode of a gaseous discharge or thyratron type tube 13, preferably of the model known in the trade as Type.#2D21.

The cathode of the tube is connected directly to ground while the igniter is negatively biased by a connection through a 470,000 ohm resistor to a source 14 of B minus potential, thereby normally maintaining the tube in non-conducting condition.

A capacitor 15 is provided, its lower terminal being connected to ground and its upper terminal being connected to one of a pair of normally open contacts 16 on the relay 11, the other contact being connected to ground.

The upper terminal of the capacitor 15 is also connected through point 17 to the transfer contact 18 of a cam operated single pole double throw switch 19. The switch is normally spring held in its illustrated position completing a charging circuit through normally closed contact 20 and through normally closed contacts 21 on relay 11 to the B plus supply 12.

. Normally open contact 22 is connected at point 23 to the anode of tube 13 and to the upper end of the relay coil.

The normally open contact 24 of the switch 19 is connected through a one megohrn resistor 25 to the tube igniter.

Considering the circuit in its illustrated condition,

2 the tube 13 is non-conducting and the relay 11 is deenergized. At this time, B plus is applied from supply 12 through contacts 21 and 20 to maintain the capacitor 15 in its charged condition.

When the switch 19 is operated to close contacts 18 and 24, the capacitor 15 is discharged, thereby raising the potential of the tube igniter above its critical con' trol point so that the tube will conduct. Accordingly, a circuit will be completed through the relay coil to ener gize the relay.

Since the inherent operation of a thyratron type tube is such that once fired, it will remain conducting, even after the potential of its emitter is dropped below the critical point, the relay will remain energized and the tube 15 will remain conductive even after the switch 19 has returned to its normal condition.

As a consequence of contact 16 closing, the latter will apply ground potential to the upper terminal of the capacitor 15 to insure complete discharge thereof. Also, relay contacts 21 will have opened to remove B plus potential from the capacitor.

Now, as the contacts 20 close, ground potential is ap plied from point 17 through contacts 20 and 22 to point 23, thereby simultaneously establishing a locking or holding circuit for the relay coil and, by virtue of grounding out the anode of tube 13, rendering the latter nonconductive. Since at this time the igniter is biassed below ground potential, the tube will remain non-con ductive.

Upon the second actuation of the switch 19, the contacts 18 and 20, upon opening, break the holding circuit for the coil, permitting the relay to become deenergized. Even though contacts 18 and 24 close at this time, the tube will not be fired since there is no charge on the capacitor at this time. However, when the switch 19 returns to its normal position, B plus will again be applied through contacts 21 and 20 to the upper tenninal of the capacitor to charge the same so that upon the third actuation of the switch, the tube will again be fired as described hereinabove to energize the relay.

It will be seen from the above that the relay will assume one state or condition when energized and will assume its second state when deenergized, and may accordingly be utilized in any desired manner to control other circuits. For example, a set of transfer contacts 26 may be embodied in the relay and may be connected in any desired manner to suitable utilization circuits.

Although we have described our invention in detail in its preferred embodiment and have therefore used specific terms and languages herein, it is to be understood that the present disclosure is illustrative rather than restrictive and that changes and modifications may be resorted to without departing from the spirit or scope of the claims appended hereto. For example, the switch 19 may be operated manually or by any other means.

Having thus described our invention, what we desire to secure by United States Letters Patent is:

1. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; said anode and cathode being in circuit with the winding of said relay and with a source of potential, means normally biasing said igniter to prevent firing of said tube, a capacitor, a circuit for charging said capacitor comprising normally closed contacts in said relay; means for discharging said capacitor into said igniter whereby to fire said tube, and a locking circuit comprising normally open contacts in said relay for concomitantly locking said relay in energized condition and for rendering said tube non-conducting.

2. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; said anode and cathode being in circuit with the winding of said relay and with a source of potential, means normally biasing said igniter to prevent firing of said tube, a capacitor, a circuit for charging said capacitor comprising normally closed contacts in said relay; means for concomitantly opening said charging circuit and discharging said capacitor into said igniter whereby to fire said tube, and a locking circuit comprising normally open contacts in said relay for concomitantly locking said relay in energized condition and for rendering said tube nonconducting.

3. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; said anode and cathode being in circuit with the winding of said relay and with the source of potential, means normally biasing said igniter to prevent firing of said tube, a capacitor, a circuit for charging said capacitor comprising normally closed contacts in said relay and a normally closed switch means; means for concomitantly opening said switch means and discharging said capacitor into said igniter whereby to fire said tube, and a locking circuit comprising normally open contacts in said relay in series with said switch means for concomitantly locking said relay in energized condition and for rendering said tube non-conducting.

4. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; connections for a voltage source comprising high potential and low potential terminals; said high potential terminal being connected to one end of the winding of said relay, said low potential terminal being connected to said cathode, said anode being connected to the other end of said winding, means normally biasing said igniter to prevent firing of said tube, a capacitor connected at one side to said low potential terminal, a charging circuit comprising normally closed contacts in said relay connected between the other side of said capacitor and said high potential terminal, means for discharging said capacitor into said igniter whereby to fire said tube, and a locking circuit comprising normally open contacts in said relay between said low potential terminal and said other side of said capacitor and a second set of normally open contacts in said relay between said other side of said capacitor and said anode for concomitantly locking said relay in energized condition and for rendering said tube non-conducting.

5. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; connections for a voltage source having high potential and low potential terminals, said high potential terminal being connected to one end of the winding of said relay, said low potential terminal being connected to said cathode, said anode being connected to the other end of said winding, means normally biasing said igniter to prevent firing of said tube, a capacitor connected at one side to said low potential terminal, a charging circuit comprising normally closed contacts in said relay connected between the other side of said capacitor and said high potential terminal, switch means for concomitantly opening said charging circuit and for connecting said other end of said capacitor tosaid igniter whereby to fire said tube, and a locking circuit comprising normally open contacts in said relay between said low potential terminal and said other side of said capacitor and a second set of normally open contacts in said relay between said other side of said capacitor and said anode for concomitantly locking said relay in energized condition and for rendering said tube non-conducting.

6. A bi-stable switching circuit comprising a relay, a normally non-conducting gaseous discharge tube having an anode, cathode and igniter; said anode and cathode being in circuit with the winding of said relay and with a source of potential, a capacitor, a circuit for charging said capacitor comprising a first set of normally closed contacts in said relay, and a second set of normally closed contacts; means comprising a third set of normally open contacts for connectingsaid capacitor to said igniter whereby to fire said tube; means for concomitantly opening said second set and closing said third set, and a locking circuit comprising a fourth set of normally open contacts in said relay connected in series with said second set for locking said relay in energized condition and for rendering said tube non-conducting.

7. A bi-stable switching circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; connections for a voltage source having a high potential terminal and a low potential terminal, said anode being connected to one end of the winding of said relay, the other end of said winding being connected to said high potential terminal, said cathode being connected to said low potential terminal, means normally maintaining said igniter at a lower potential than said cathode whereby to maintain said tube non-conducting, a capacitor having one side connected to said low potential terminal, a circuit connected between said high potential terminal and the other side of said capacitor and comprising a first set of normally closed contacts and a second set of normally closed contacts in said relay for charging said capacitor; means comprising a third set of normally open contacts for connecting said other side of said capacitor to said igniter whereby to fire said tube; means for opening said first set of contacts and for closing said third set of contacts, and a circuit between said low potential terminal and said anode comprising fourth and fifth sets of normally open contacts in said relay, said fourth set. being eflfective to connect said low potential terminal to said other side of said capacitor and said fifth set being effective to connect said first set of contacts to said anode and to said one end of said winding whereby to cause said tube to become non-conductive and to lock said relay in energized condition,

8. A bi-stable circuit comprising a relay, a gaseous discharge tube having an anode, cathode and igniter; said anode being connected to one end of the winding of said relay, connections for a voltage source comprising a high potential terminal and a low potential terminal, the other end of said winding being connected to said high potential terminal, said cathode being connected to said low potential terminal, means normally biasing said igniter to maintain said tube non-conducting, a capacitor having one side connected to said low potential terminal, a circuit connected between said high potential terminal and the other side of said capacitor comprising a first set of normally closed contacts in said relay for charging said capacitor; means for concomitantly breaking said charging, circuit and for connecting said other side of said capacitor to said igniter whereby to fire said tube, and a locking circuit between said low potential terminal and said one side of said winding comprising second andv third sets of nor mally open contacts in said relay, said second set being effective to connect said low potential terminal to said other side of said capacitor and said third set being efiective to connect said other side of said capacitor to said anode and to said one side of said winding whereby to cause said tube to become non-conducting and to lock said relay in energized condition.

References Cited in the file of this patent UNITED STATES PATENTS 1,552,321 Lea Sept. 1, 1925 1,901,663 Minkler Mar. 14, 1933 2,559,508 Meier July 3, 1951 2,697,802 Decker et al Dec. 21, 1954 FOREIGN PATENTS 614,472 Great Britain Dec. 16, 1948 

